Watch out for poison oak & ivy

The summer is a time for camping, hiking, gardening, and enjoying the outdoors. Unfortunately, this can also become a popular time for poison ivy, poison oak and poison sumac outbreaks. Upon your skin touching these plants' oils, a red itchy rash can show up in the form of lines and streaks, or blisters and hives. In order to help prevent breaking out in an annoying rash, keep the following information in mind and enjoy the outdoors!

Poison ivy, oak and sumac are the leading culprits behind of allergic skin reactions in the United States -- with an estimated 55 million occurrences each year. If you're in the 70 percent or so of the population who is sensitive to this oil -- a colorless, odorless resin called urushiol -- you may know well the end result: an itchy rash with oozing blisters.

Detecting the symptoms

The rash from poison ivy/poison oak (Rhus dermatitis) can develop anywhere from 30 minutes to five days after the exposure, and can last anywhere from 10 days to three weeks. The timing and severity of the outbreak depends on how sensitive you are, how much contact was made with the poison plant, where exactly on your skin you were exposed, and if you've had a reaction before. (It may take more than a week to show up the first time you come in contact with the plant's oil, but it tends to develop more quickly with each outbreak.)

"The allergic reaction from poison ivy is caused by oil in the plant," says Lisa Hammer, MD, a pediatrician at the University of Michigan CS Mott Children's Hospital. "The reaction usually starts with redness and swelling of the skin, which is then followed by either bumps or blisters."

Swelling of the face, mouth, neck, genitals or eyelids (which may prevent the eyes from opening).

Widespread, large blisters that ooze large amounts of fluid.

Keep in mind that the rash can develop in new areas over several days (though this nearly always does not mean that the oils have spread -- just that the urushiol is taking its time). NEXT PAGES: What to do if you get a poison ivy/oak rash & how to recognize the plants